This invention relates to a control system for a valve, especially a seating valve, whose valve body is displaced into one end position by spring action.
Control systems for valves are known (SAE Technical Paper, Series 801018, Electronic/Hydraulic Hitch Control for Agricultural Tractors), and serve to control the flow of a pressure medium, especially oil, to a load or away therefrom.
On account of the great expenditure of positioning force in such control systems, there are used a three-part main control valve and two separate pre-control valves, the main control valve being set under pressure action controlled by the precontrol valve. The pre-control valve is set to its different positions by means of electromagnets.
Such control systems are expensive and influenced by the tightness of the assembly and by fluid viscosity. The valve adjustment stroke is force-dependent and is therefore influenced by viscosity and back pressure.